Voltage isolators or galvanic isolators prevent direct current (DC) flow between two circuits. In other words, galvanic isolators eliminate DC paths. In addition, galvanic isolators enable data communication between two circuits. Galvanic isolators are often used when two circuits must communicate with each other, while their grounds are at different potentials.
There are several different types of galvanic isolators. A transformer is a galvanic isolator. Transformers isolate circuits, but enable data signals to pass between the circuits through use of magnetic flux. Optocouplers transmit data signals by light waves. The sender (e.g., light emitting diode) and receiver (photosensitive device) are not electrically connected. Capacitor based isolators use an electric field to transmit data signals across capacitor isolation barriers. U.S. Pat. No. 6,389,063 illustrates one or more examples of galvanic isolators.